1. Field of the Invention
This invention relates to a housing for a riflescope and particularly a riflescope housing which is constructed of a carbon fiber material.
2. Description of the Prior Art
In the past, riflescope housings, mainly have been constructed of various aluminum alloys with some being constructed of steel. This material has been nearly universally adopted as the material of choice as it offers several desirable features. First, alloyed aluminum is easily machined which is of significant value considering the amount of machining required to produce a riflescope housing. Second, aluminum is generally considered to be light weight, yet offers substantial strength. And lastly, aluminum may be treated to resist corrosion and weathering and also to impart color to the surface.
Accordingly, for the reasons set forth above, aluminum alloy has become the standard of the industry when selecting a material for use as a riflescope housing. These materials are chosen because of their machinability, extrudability, acceptable tensile strength ratings and ability to accept anodization treatment.
However, even in view of the advantages cited for the use of aluminum in the construction of riflescope housings, there exist several distinct problem areas which, up until the riflescope of the present invention, have yet to be addressed. For example, although aluminum is easily machined, the machining process itself can be quite costly. Also, aluminum must be treated, such as by anodization, to provide corrosion resistance and color to the material. This treatment adds further to cost. Further, and quite importantly, aluminum alloys are subject to changes in environmental conditions. That is, their coefficient of thermal expansion is such that the material either contracts or expands as the ambient temperature changes. Obviously, this factor can present a substantial problem for a hunter who may encounter rather drastic changes in temperature while pursuing his hobby. For example, the hunter may be leaving the confines of a hunting cabin where the temperature would be, perhaps, 65.degree.-75.degree. C. and entering the outdoor hunting environment where the temperature commonly falls below freezing, and in many instances well below freezing. This drastic change in temperature has a causal effect on the integrity of the optics mounted within the riflescope housing even if the optics are mounted in a material similar to the riflescope housing. This is so because the housing would be effected by the temperature change and caused to contract well before the internal mounts holding the optics. The movement of the materials with respect to each other many times causes the optics to lose collimation which is a serious problem with any sports optics device. Additionally, the relative movement of dissimilar materials may result in binding of the power change mechanism in adjustable focus riflescopes.
The problem is even further exacerbated when going from a cold environment to a warm environment. In this instance, the housing expands much more rapidly than the internally mounted optics, and as such the optics become loose and are essentially able to move within the scope housing. In some instances, this can be evidenced by a rattling sound and later by the previously referenced loss of collimation of the light rays passing through the optics of the instrument.
The above-referenced problem is still further complicated when dissimilar materials are utilized in the construction of the riflescope. As more dissimilar materials are used in construction, the various differences in thermal coefficients of expansion of the materials have a greater effect on the performance of the device.
A further consideration is the strength factor of the chosen aluminum alloy. Generally, aluminum alloys are chosen from either the 5000 or 6000 Series of alloys whose specifications and performance factors were defined by the ASTM. Some commonly used aluminum alloys include 5045T5, 6061T6 and 6063T6. The tensile strength of the alloys ranges from about 30,000 P.S.I. to 40,000 P.S.I., dependent upon choice. Other alloys are available which have much greater tensile strength ratings, but these materials are not used because of problems encountered in manufacturing and application of surface treatments.
Therefore, most riflescope housings manufactured today are of aluminum alloys which afford very low tensile strengths when compared to other known materials. As such, the housings are readily damaged by incidents which occur on a frequent basis in the hunting environment. As an example, it is not uncommon for a rifle bearing the scope to be dropped or knocked over. Many times such accidents render the scope unusable because of physical damage to the housing which, in turn, effects the scope's optical accuracy.
Composite and plastic materials also have been used for the manufacture of sports optics instruments, such as binoculars, as is evidenced by U.S. Pat. Nos. 3,531,177; 4,056,303 and 4,436,386. However, these materials offer very little strength, and in fact are considerably weaker than aluminum alloys or steel. Consequently, they are rarely, if ever, used for riflescopes.
Tubular members which are manufactured from materials other than steels or aluminum alloys have, of course, been known for some time. However, such tubular members are found in areas very diverse from the sphere which includes riflescopes and sports optics. For example, tubular housings constructed of, plastics, fiberglass and carbon fiber have been known. Uses for such tubes may vary from drivershafts for the automotive and trucking industry to enclosures and holders for fuses used in commercial wiring applications. However, as stated, the application is quite far removed from the sports optics field. An example of a composite tubular member constructed of filaments may be seen in U.S. Pat. No. 3,970,495. Other examples of composite tubular members may be seen in U.S. Pat. Nos. 3,414,960; 4,039,006; 4,047,731; 4,089,190; 4,157,181; 4,171,626; 4,173,128; 4,248,062; 4,301,201; 4,469,138; 4,605,385 and 4,657,795.
From the above, it is obvious that there is a strong need and desire to have provided a riflescope which is strong, yet light weight; easily manufactured from available materials and relatively unaffected by changes in climatic conditions.
The primary purposes of the present invention, as set forth and described in detail hereinafter, are to provide such a riflescope.